The corporation assignee of this application has produced tubular packages or containers over the last 15 years as exemplified by U.S. Pat. No. 3,986,659, issued Oct. 19, 1976 entitled "END CAPS FOR TUBULAR CONTAINERS; " U.S. Pat. No. 3,913,774, issued Oct. 21, 1975 entitled "END CAPS FOR CONTAINERS"; and U.S. Pat. No. 4,700,883, issued Oct. 20, 1987 and entitled "TUBULAR PACKAGE AND END CAP FORMING COMPONENT OF SAME" wherein, a hollow, rectangular, clear plastic tubular sleeve, is normally formed of a thermoplastic material, approximately 0.005-0.02 inches in thickness, and held to a preformed polygon shape by rigid end caps locked thereto.
The patents identified above exemplify the use of tabs projecting outwardly from edges of rigid end caps formed of the same thermoplastic sheet material which forms the flexible tubular sleeve, which tabs are insertable within elongated slots formed within the opposed walls of the tubular sleeve at the ends receiving the rigid end caps.
Such arrangements obviated the prior use of adhesive, tape, staples and other fasteners which were unsightly or enlarged the tubular sleeve, the end caps or both.
In the development of such display packages or containers, supports for the articles packaged within the transparent plastic sleeve have been created from folded cardboard or other flexible sheet material, functioning additionally as, end caps or inserts within the open opposite ends of the tubular sleeve.
U.S. Pat. No. 3,608,705 issued Sept. 28, 1971 exemplifies such display package including a support of cardboard flexible sheet material. In U.S. Pat. No. 3,608,705, the support is made up of two parts of folded cardboard. A rectangular article support base locks to a hollow cardboard parallelepiped tube insert by way of slits formed within each hollow insert wall closing off the open end of the tubular sleeve and arrow headed tabs project as extensions from opposite ends of the support base panel aligned with the slots and projecting therethrough.
Such tab and slot connection had been employed additionally in locking a base to a cover in U.S. Pat. No. 4,782,977 issued Nov. 8, 1988 and entitled Tamper Resistant Container; locking a lid to a preformed container both formed of cardboard flexible sheet material. In U.S. Pat. No. 4,923,113 issued May 8, 1990 and entitled "CONTAINER WITH A PERFECTED LID"; coupling of molded plastic rigid end caps into opposite ends of a polygonal cross-section clear plastic shell body is effected by holes within the wall of the shell body at opposite ends aligned, and the end cap, via pin-like integrally molded lugs which extend inwardly from flexible flaps molded integrally with the edge of the end cap wall closing off the open end of the shell body and being a length so as to extend along the outer surface of the shell body wall.
In the production of such tubular packages, due to the thinness of the extruded or nonextruded clear plastic material forming the basic stock material for the sides of the tubular sleeve, the end caps or closures for the sleeve must be relatively rigid and have sufficient structural strength to maintain the integrity of the container or package once completed and to support the article packaged within the tubular sleeve as well as prevent inadvertent separation of the end caps from the tubular sleeve.
It is therefore the primary object of the present invention to provide an improved, low cost, reinforced folded cardboard end closure for a tubular container which self locks to the transparent tubular sleeve, which resists separation of the end closure from the sleeve, which may be formed of a single cardboard precut blank, which provides an attractive addition to the transparent sleeve, and which completes a highly stable, rigid connection therebetween.